Power module is an integrated component or module capable of processing electricity, and it is integrated by different components and technology according to optimum electrical circuit structure and system structure. Multiple power modules can work together to constitute a power electronics system, so as to achieve systematic functions such as voltage transformation, energy storage and conversion, and impedance matching. For medium and high-voltage frequency converter, multiple power modules in a cabinet are usually connected in series to regulate power. In order to make the system structure compact, it is necessary to compact the structure of power module in the cabinet while optimizing cooling of the power module.